Letter-coding conveyor



June 25, 1968 HEANEY ETAL 2 Sheets-Sheet 1 Filed Oct. 17, 1966 ATTORNEY United States Patent M 3,389,909 LETTER-CODING CONVEYOR Richard Heaney, Campbell, and Derek Hall, Los Gatos, Calif, assignors to FMC Corporation, San Jose, Calif., a corporation of Delaware Filed Oct. 17, 1966, 8 1-. No. 587,301 9 Claims. (Cl. 271-74) ABSTRACT 0F THE DISCLGSURE A stationary magnetic head is mounted on the apertured face of a vacuum box adjacent the reach of a perforate belt in sliding contact with said face. Vacuum slots at each side of the magnetic head are evacuated with a higher negative pressure than the vacuum pressure applied to the belt reach. A letter conveyed by the belt reach thus has a relatively large area subjected to one vacuum pressure, and a relatively small area that overlies the magnetic head and is subjected to a high vacuum pressure. The vacuum box is compartmented to prevent excessive loss of vacuum pressure when the document is not in complete masking relation with the vacuum box apertures.

This invention pertains to a letter-coding conveyor and more particularly to a conveyor for moving a letter past a magnetic head at a constant velocity and in positive coding contact therewith.

When sorting mail with one type of automatic processing equipment, it is essential that complete code sorting information be marked on each letter to enable accurate distribution. Such code marking is achieved by spraying a strip of the letter with magnetic ink and the coding information is printed thereon by a magnetic printing head. A magnetic reading head is used to check the coding and transmit the information to an electronic directory which contains the necessary information for diverting letters at the proper transfer points. The magnetic printing and reading operations are similar to those of a magnetic tape recorder and thus have similar requirements. The letter must move at a constant velocity as it passes the printing and reading heads, while positive sliding contact must be maintained between the respective heads and the magnetic ink strip on the letter. Since letters usually have a somewhat curved transverse cross section which varies in thickness, positive contact for coding is difiicult to maintain. Impositive contact can cause slippage of the letter on the conveyor and alter the velocity of the letter as it passes the magnetic heads so as to vary the recording or playback speed. Proper letter coding is achieved by use of the letter coding conveyor of the present invention, which overcomes these problems and meets the foregoing requirements.

An object of the present invention is to provide a conveyor for transporting letters of various thicknesses in sliding, constant velocity contact past a magnetic head.

Another object of the invention is to maintain positive printing and reading contact with such letters as they are conveyed past a magnetic head.

A further object of the invention is to maintain letter adherence to the conveyor of a magnitude sufficient to overcome the opposing friction forces set up by positive contact with the magnetic heads.

Other objects and advantages of the invention will be apparent from the following detailed description, reference being made to the annexed drawings, in which:

FIGURE 1 is a perspective view of a letter coding conveyor embodying the present invention.

FIGURE 2 is a horizontal section of the conveyor taken on the line 2-2 of FIG. 1.

3,389,9b9 Patented June 25, 1968 FIGURE 3 is a vertical section of the conveyor taken on the line 3-3 of FIG. 2.

A letter-coding conveyor 10 is shown in FIG. 1 having a frame member 12 upon which a plate 14 is mounted. A channel 16 extends longitudinally of the plate providing a passage for the lower portion of a letter L, as shown in FIG. 3. A housing 18 is mounted on the plate along one side of the channel and has a pair of magnetic heads 20 and 22 (see FIG. 1) fitted therein, positioned to face inwardly toward the channel. Magnetic head 20 is for printing coding information on a strip S of the letter L which has been sprayed with magnetic ink. Magnetic head 22 is used for reading the magnetic coding marked on the letter by head 20. These magnetic print and read heads are standard electronic components readily available on the commercial market, such as those manufactured by The Nortronics Company, Inc. of Minneapolis, Minn. A vertical suction slot 24 is positioned within the housing at the right and left sides of each magnetic head. A vacuum line 26 (see FIG. 3) links each suction slot with a source having a low volume high vacuum head of about 15 inches of mercury. This suction draws the surface of the letter adjacent the magnetic head into contact therewith and smooths out surface wrinkles as the letter is drawn past the head for coding purposes.

A resilient roller 28, made of sponge rubber or the like, is positioned above the channel 16 opposite the magnetic head 20, while a similar roller 30 is positioned opposite the magnetic head 22. These rollers are supported by similar mounting means and so like parts will be identified by like numerals. Each roller is journalled on a separate axle 32 which extends vertically between a top plate 34 and a bottom plate 36. The axle is held in place between the plates by lock washers 38, as shown in FIG. 3, at each end of the axle. Spacing between the plates is maintained by a sleeve 40, as shown in FIG. 2, which acts as a spacer, and by a separate connecting pin 42. A spring 44 is secured to the connecting pin and is bent about the sleeve with contact end 46 projecting tangentially therefrom. A bolt 48 passes through the spacer sleeve and plates and is threaded into the plate 14. This bolt serves as a pivot pin about which the top and bottom plates holding the roller are free to pivot. A stop block 50 is secured to the plate 14 adjacent the roller mounting means by bolts 52 and 54. A contact pin 56 projects inwardly from the block to engage the contact end 46 of spring 44. Thus, it will be seen that the roller mounting means are free to pivot outwardly from the magnetic head on bolt 48 but in doing so, resilient energy is stored within the spring upon contact with pin 56 to return the mounting means and roller to their original position.

A vacuum box 58 is positioned above the housing 18, as shown in FIG. 3, and includes a bottom panel 60, a back panel 62, a left side panel 64 (see FIG. 2), a right side panel 66, a top panel 68 and a slotted front panel 70. A divider 72, as shown in FIG. 2, separates the interior portion of the box into two suction chambers 74 and 76. Horizontal slots 77 are slotted within the front panel to provide vacuum communication between the suction chambers and the front panel exterior. A suction line 78, as shown in FIG. 1, is connected with chamber 74 through top panel 68, while suction line 80 is connected in a similar fashion to chamber 76 to provide suction within the chambers. Each suction line is connected to a vacuum source having a high volume and low head, such as 300 c.f.m. and 4 inches of mercury.

A drive shaft 82 is journalled by frame member 12 and journal plate 84, which is bolted to the top panel 63 of vacuum box 58, as shown in FIG. 1. A drive pulley 86 is mounted on the drive shaft for rotation therewith. Similarly, an idler shaft 88 projects upward from the frame member at the opposite end of plate 14 and is journalled within plate 9t) which is bolted to the opposite end of the top panel. An idler pulley 92 is fixed to the idler shaft and a perforated endless belt 94 is trained about the drive and idler pulleys 86 and 92. Upon rotation of the drive shaft, the endless belt moves in the direction of arrow 96, as shown in FIG. 1. Perforations 98 are provided within the belt and aligned in three horizontal rows to register with the horizontal slots '77 enabling communication with the suction chambers 74 and 76. The belt has an inner face 106 which contacts the pulley wheels and rides against the slotted front panel 76. Outer face 1G2 of the belt makes contact with the letter L, as shown in FIG. 3, and is aligned in a plane substantially flush with the magn tic heads 20 and 22. The overall distance D, as shown in FIG. 1, which includes the belt width, spacing and magnetic head is less than the normal width of a letter, as shown in FIG. 3.

In operation, letters are fed to the otter coding conveyor 16 by means, not shown, and diverted into contact with the perforated belt 94 near the pulley wheel '92. The vacuum within chamber 74 creates a suction through horizontal slots 77 and perforations 98 so that the letter adheres firmly to the belt, as shown in FIG. 3. Since the divider 72 separates the vacuum box 58 into two suction cham ers, the exposure of suction chamber 76 to the atmosphere does not bleed the adhering suction of chamber 74. The belt travels at a constant velocity and the letter moves therewith to the magnetic print head 2%. The width of the letter is greater than the width of the belt and therefore, a portion of the letter lies below the belt. On this depending portion, a strip S has previously been sprayed with magnetic ink and is aligned to contact the magnetic print head. Contact is made between the head and the ink strip since the outer face 102 of the belt is aligned in a plane substantially flush with the head. Suction from slots 24 further insures positive contact by drawing the strip against the head and smoothing out surface Wrinkles. The resilient roller 28 presses against the opposite side of the letter from the ink strip forcing it against the head and helping the suction slots to attract the letter surface. This roller is particularly helpful when the letter is bent or wrinkled. Since the roller rotates on axle 32 and is mounted to pivot outwardly about bolt 48 in the event of thick letters, excessive friction is not created which might overcome the adhering suction between the letter and belt. Thus, the letter travels at a constant velocity past the magnetic head in positive coding contact therewith.

In a similar manner, the letter L is conveyed past the magnetic read head 2. Positive coding contact is assured by the belt alignment with the magnetic head, the suction from slots 24 which draws the letter against the head, and the resilient roller 30 which applies a back pressure to the letter. As the letter moves to cover the slots 77 of suction chamber 76, adhering suction builds up to hold the letter to the perforated belt 94. Suction chamber 74 is exposed to the atmosphere but divider 72 prevents the bleeding of suction between chambers. The letter is thus conveyed to a point adjacent the pulley wheel 86, where it is diverted by means not shown to subsequent conveying means, also not shown.

This letter coding conveyor is particularly suitable for letters of various thicknesses because a letter is contacted for conveying and coding purposes primarily on one one side only. The resilient rollers 28 and 30 which do contact the opposite side of the letter are made of soft sponge rubber or the like which will deflect under pressure and the roller assembly will pivot on bolt 48, outwardly from the letter in response to excessive pressure.

Although the best mode contemplated for carrying out the present invention has been herein shown and described, it will be apparent that modification and variation may be made without departing from what is regarded to be the subject matter of the invention as set forth in the appended claims.

We claim:

1. Letter-handling apparatus for moving a letter endwise at a constant velocity comprising a stationary magnetic head, a perforated endless belt driven at a constant velocity and having a reach movable alongside said magnetic head, said reach having an outer face substantially coplanar with the outer face of said magnetic head and arranged to drivingly engage one flat side of a letter, the linear dimension across said belt reach, said magnetic head and the space therebetween being less than the corresponding dimension across the fiat side of the smallest letter to be moved by said conveyor, and a vacuum box having a perforate face slidably engaged by said belt reach, the negative suction pressure thus induced on the face of said belt reach creating a pressure differential between the sides of the letter to adhere one portion of one side of the letter to said reach, an adjacent portion of the same side of the letter thereby being in sliding contact with said magnetic head.

2. A conveyor as described in claim 1, including a resilient roller pivotably mounted opposite said stationary magnetic head for resiliently urging the letter against the magnetic head.

3. Apparatus according to claim 1 wherein said vacuum box is divided into a plurality of suction chambers successively spaced along the path of travel of said belt reach to prevent excessive loss of the suction applied to the letter when the letter is out of masking relation with the perforate face of said vacuum box as it moves with said belt reach.

4. Apparatus according to claim 3, wherein said vacuum box suction chambers are evacuated to a low vac uum pressure with a high volume capacity.

5. Apparatus according to claim 4 and means defining a suction slot adjacent said magnetic head, said slot being connected to a low volume capacity and high vacuum pressure source whereby the suction at said slot draws the letter into positive coding contact against the magnetic head.

6. Apparatus according to claim 1 wherein said vacuum box is evacuated to about four inches of mercury at a capacity of about three hundred cubic feet per minute.

7. Apparatus according to claim 1 and means defining two suction slots straddling said magnetic head in the direction of movement of said belt reach, said suction slots being connected with a higher negative pressure source than the negative pressure existing on the face of said belt reach to draw the letter surface traversing said magnetic head into positive coding contact with said head.

8. A conveyor as described in claim 7, including a resilient roller pivotably mounted opposite said stationary magnetic head for resiliently urging the letter against the magnetic head and into position for said suction slots to draw the letter into positive contact therewith.

9. The apparatus of claim 7 wherein said suction slots are evacuated to a vacuum pressure of about fifteen inches of mercury.

References Cited UNITED STATES PATENTS 3,198,517 8/1965 Martin 271-74 0 RICHARD E. AEGERTER, Primary Examiner. 

